A pressurized screen for the screening of pulp suspensions comprises an airtight housing, in which a screening member is located. The housing has an inlet for the pulp suspension and outlets for accept and rejection portions, respectively. In order to promote the screening process, the pulp suspension is caused to flow along the screening member, and the accept portion passes through the screening member, which can be rotary or stationary. In the latter case, the rotor is located in the housing for generating the flow along the screening member.
The rotor of the rotary screening member in such devices is mounted on a shaft, which is driven by a motor located outside the housing. The shaft is supported in bearings and extends into the housing. The housing is pressurized and, therefore, a seal is provided where the shaft enters the housing. In order to provide stability for the shaft, an internal axial bearing is located in an airtight casing, which extends into the housing. The seal is mounted in a seal holder between the casing and the interior of the housing inside the internal bearing.
This structural design has the disadvantage that the external (atmospheric) side of the shaft seal is accessible only after the entire shaft with its bearings has been dismounted. This results in the fact that conventional shaft seals of the mechanical seal type, for example a so-called cartridge seal, cannot be applied. In many cases this is a considerable disadvantage, because it requires complicated structures and lengthy dismantling work at the time of seal exchange.
The present invention has the object of eliminating the aforesaid problems. The device according to the present invention, therefore, renders it possible for the shaft seal side located outside the container, i.e. in the casing, to be made accessible during seal exchange in a simple manner.